How do you stop everyone in Europe from taking all their Euros and changing them into NDM ('Neue Deutschmark')?
Only the X serial numbers come from the Bundesbank
With mausers and lugers?
Very good question. All euro bills are valued the same, whether they are marked ‘X’ or whatever. They’re spread out all over Europe and the world anyway. (It’s not like you change your ‘X’ bills to ‘Y’ bills when crossing a border...)
There was massive fraud when the Ostmark was allowed to be converted to Deutsche Mark. This would open the doors to fraud many orders of magnitude greater. Even if the conversion was tied to citizenship. (”Hey Achmed, since you’ve got a German passport, convert these billions of euros to the new Deutsche Mark for me, will ya?”)
The only viable way I see would be a currency reform like after WW II - everyone gets a few hundred new Deutsche Mark and there you go. Back to square one. Don’t complain, please.